.bg {
    background-color:cadetblue;
    display: flex;
    flex-direction: row;
    flex-wrap: wrap; /*自动换行*/
    /* justify-content: flex-start; 靠左对齐 */
    justify-content: space-around;
    align-items: flex-end; /*交叉轴终点对齐*/
}
.bo {
    border: 2px solid yellow;
}
.item {
    display: inline-block;
    width: 50px;
    height: 50px;
    background-color: rgb(156, 43, 43);
}
.item2 {
    display: inline-block;
    width: 80px;
    height: 80px;
    background-color: darkgreen;
}